1. Technical Field of the Invention
This invention relates to Mannich condensates useful in the manufacture of rigid polyurethane foam. More particularly, this invention relates to modified Mannich condensates, to the manufacture from their propoxylation products, and to the synthesis therefrom of rigid polyurethane foams having improved fire retardancy properties. The invention is based upon the discovery that unique polyols are provided when melamine is reacted with formaldehyde in the presence of a particular class of Mannich condensates to provide a reaction product that is then alkoxylated with propylene oxide.
2. Prior Art
Johnson U.S. Pat. No. 4,369,258 is directed to polyurethane foams prepared by reacting a polyisocyanate with a mixture of a melamine polyol with a polyol derived from a polyester or a polyether polyol.
Yukuta et al. U.S. Pat. No. 4,221,875 is directed to rigid polyurethane foams having flame resistance which are prepared from a mixture comprising a polyhydroxy compound such as an ethylene oxide adduct of a material containing a plurality of hydroxyl groups such as sucrose or sorbitol, an organic polyisocyanate, a blowing agent and powdered melamine. From 20 to 60 parts by weight of powdered melamine per 100 parts of polyhydroxy compound are recommended.
Pcolinsky, Jr. U.S. Pat. No. 4,317,889 and the numerous U.S. patents cited therein disclose the use of melamine derivatives such as hydroxymethyl melamines, melamine phosphate, hexaalkoxymethylmelamine, etc. as a component for use in the manufacture of flexible polyurethane foams.
Edwards et al. U.S. Pat. No. 3,297,597 is directed to Mannich condensates of a phenolic compound, formaldehyde, and an alkanolamine which are then alkoxylated, preferably with propylene oxide, to provide polyols useful in the manufacture of rigid polyurethane foams.
Edwards et al. U.S. Pat. No. 4,137,265 is similarly directed to Mannich condensates prepared by reacting phenol with formaldehyde and diethanolamine which are then propoxylated and used in the manufacture of rigid polyurethane foam.